A single stage amplifier generally includes one transistor, a bias circuit, and other components. Single stage amplifiers may be categorized as either a common-gate amplifier, a common-drain amplifier, or a common-source amplifier, depending on which terminals of the transistor a signal enters and exits. The terminal in which the signal does not enter nor exit is referred to as the “common terminal.”
In a common-gate amplifier, the source terminal serves as the input, the drain terminal serves as the output, and the gate is generally connected to ground or a common voltage. In a common-drain amplifier, the gate terminal serves as the input, the source terminal serves as the output, and the drain terminal is common. In a common-source amplifier, the gate terminal serves as the input, the drain terminal serves as the output, and the source terminal is common.
An ideal amplifier has high gain (e.g., DC gain) and high bandwidth (also known as 3 dB loss frequency). In some amplifiers, the 3 dB loss frequency may be increased by providing frequency peaking. However, in these amplifiers, the DC gain is typically reduced in order to provide the frequency peaking.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention, and therefore, it may contain information that does not constitute prior art.